Structural damage detection based on improved Hilbert-Huang transform

Aiming at the problem of mode mixing in signal analysis by using Hilbert-Huang transform (HHT), an improved HHT method based on ensemble empirical mode decomposition (EEMD) was introduced and applied in the identification of structural damages. A three degrees of freedom bilinear stiffness degradation model of shear type structure was established. Structural responses under earthquake were calculated and analyzed by the improved HHT. A method to detect the location of damage based on intrinsic mode function (IMF) energy was proposed. It is shown that whether or not a structure is damaged and when the damage occurs can be decided by an instantaneous frequency change of structural acceleration and the location of damage is detected by the variation of corresponding IMF energy at the first modal frequency of structural response before and after damage. The damage of an actual engineering under earthquake can be well identified by extracting the first modal instantaneous frequency and the first modal IMF energy. ©, 2015, Chinese Vibration Engineering Society. All right reserved.